University Communications

Narrator: Travel down this country road in Greensborough, Vermont and you'll find sunk in a hillside, a building that cheesemakers consider one of the seven wonders of the world.

The Cellars at Jasper Hill houses seven underground cheese caves, perhaps the largest facility of its kind on earth. The 22,000 sq. ft. structure is buried at the perfect depth for aging cheese naturally, in the open air, which gives it both subtle flavor -- and a high price point.

Andy Kehler: The floor in the back is 27 feet below grade. We can maintain this without any electricity at the exact temperature and humidity that we want, which is about 52 degrees and 90-93% relative humidity.

Narrator: Kehler, a University of Vermont alumnus, created the Cellars with his brother Mateo so Vermont's thriving community of artisan cheese-makers could do what they do best – produce high quality milk and raw cheese. Cheesemakers could then count on the Kehlers for the complex art of cheese aging – or affinage. Since it opened in 2007, 14 Vermont cheese-makers now age their cheeses at the Cellars, winning some of world's top cheese-making prizes in the process.

In their quest to boost Vermont's reputation as a cheese-making mecca, things have gone exceptionally well for the Kehlers -- with one small exception.

Kehler: The issues is that as the cheese ages, it creates ammonia, and ammonia can be detrimental to both the quality of the cheese and the people working in the space. So, we need to evacuate the air and replace it with fresh air.

Narrator: Conditioning four Vermont seasons' worth of fresh air to match the cool, moist air of the caves, it turned out, was no simple job. The engineers who designed Kehler's HVAC system were used to creating environments for people, not cheese.

Kehler: So they engineered a system that has forces working against each other. The heat from the steam generators causes the refrigeration to come on, which dries the room down, which makes the heat come on, with dries the room down, which makes the heat come on.

Narrator: After two years of trying to solve his problem with new technology and low-tech fixes like opening cave doors to vent ammonia, Kehler was still unable to precisely control the cheese aging environment. Frustrated, he decided to take a new approach.

Kehler contacted UVM's College of Engineering and Mathematical Sciences with his problem. He was invited to present to a class of senior engineering students looking for a capstone design project.

Adam Wood, UVM senior: He just kind of came in and said, "I have this cheese cave, I have this problem. I need it fixed."

It hasn't been fixed so far. I've hired professional HVAC guys and they haven't fixed it. What can you do for me? And that really intrigued me and made me want to work on it.

Narrator: Fresh eyes, it turned out, were just what Kehler's cheese caves needed. A team of four students -- Adam Wood, Paul Veselka, Evan Johanson, and Dave McCloskey -- approached Kehler's problem with energy and no preconceptions. After weeks of research, students settled on a solution coal plants commonly use to reduce pollutants: running emissions, which include ammonia, through water. The water forms a chemical bond with the ammonia, effectively scrubbing it from the air. But the two applications were worlds apart.

Wood: They do it on a (scale of) like, millions and millions of cubic feet per minute of gas. And in this application, it's not even close to that magnitude. So the idea has been proven, but the scale is completely different.

Narrator: To see if a small scale version of the technology could work, and to gather important data for scaling it to the caves, the students built a test rig in a small room in the Perkins Building.

Evan Johanson, UVM senior: This is our prototype ammonia filter. This side represents the cave which we are trying to recreate. And this side represents our actual prototype system, where we are bubbling the water through the air. Here is the ammonia which we add a finite amount of into here to represent the ammonia in the cave. Inside here we have our ammonia sensor, a computer fan to help circulate the air, and a fish tank pump. On the other side we have these four air stones that help to bubble the air up through the water. We have our water bowl, and we have a fan to help circulate the air as well.

Narrator: After months of testing variables like water depth and temperature, size of the air bubbles, and speed of the air flow to see which combination was most effective -- the students were confident they had a solution -- and were ready to try it out in the real cave environment.

On a sunny day in April, students entered the carefully controlled environment of the cheese caves.

Kehler: OK, Is everyone signed in?

Narrator: In a room stocked with aging cheddar, they set up a modified version of their test rig -- without the unneeded cave barrel.

Johanson: This is our prototype ammonia water filter. The vacuum acts as a source for the air pump. It's sucking the ammonia-rich air from the cave and filtering it through this water, and we're using a tree of PVC pipes with holes in it to create the air bubbles.

Narrator: To see if the rig was actually removing ammonia from the air, students measured the water before the test to establish a baseline -- and again after 20 minutes of run time.

With two semesters of work hanging in the balance, the atmosphere was tense.

If the experiment worked, a sensor should register an increase over the baseline of 1.2 milligrams of ammonia per liter of water.

McCloskey: It proved our whole concept really, that we can dissolve ammonia that's in the air into water.

Narrator: There was one other small matter students needed to take care of: turning in their completed project and presenting to a group of faculty and peers at the engineering college's Senior Design night.

Faculty member introducing students: The title of this presentation is "Climate Control System for Jasper Hill and Other Cheese-Aging Caves."

With Kehler and senior adviser Will Louisos in the audience, the presentation went well (applause), but the real reward came from Kehler.

Kehler: I'm encouraged. I think their foundation is solid. And they've come up with the logical solution for our problem.

Narrator: Kehler plans to introduce an inexpensive prototype into the HVAC system of one cave this summer, to see if it performs as well as the test rig -- which showed that only two-and-a-half gallons of water per day were needed to remove all the ammonia from one cave. If it does, he'll install the system in all seven caves.

Four enterprising student engineers may not only have solved Jasper Hill's problem, but laid a foundation, Kehler says, that could help address age old ammonia issues in traditional cheese-aging facilities around the world.